A Positive Feedback Onto ENSO Due to Tropical Instability Wave (TIW)‐Induced Chlorophyll Effects in the Pacific

Tian, Feng; Wang, Xiujun

doi:10.1029/2018gl081275

Cited by 15 publications

(13 citation statements)

References 52 publications

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“…The intensity of TIWs and associated fronts can be influenced by large‐scale signals, e.g., Rossby waves (Lawrence & Angell, 2000). TIW activities are enhanced during the westward propagation of Rossby waves, as this propagation increases the SST of TIWs to the north and south of the equator simultaneously (Lawrence & Angell, 2000; Tian et al., 2019). It subsequently impacts the meridional SST gradient and modifies frontal activities in the eastern Pacific Ocean (Perez et al., 2010; Thum et al., 2002).…”

Section: Interannual Variability Of Fp In the Tropical Pacificmentioning

confidence: 99%

Seasonal and Interannual Variability in the Sea Surface Temperature Front in the Eastern Pacific Ocean

et al. 2021

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The eastern Pacific Ocean, ranging from the tropical region to mid-latitudes, is an exceedingly dynamic region that has been extensively investigated during the past century. The eastern boundary currents, e.g., the California Current and Humboldt Current, are highly productive, especially in the region off Peru (Ning et al., 1998). Although the area of the coastal zone near Peru represents less than 1% of the world's ocean, it contributes more than 8% of the global fish production (Hutchings et al., 2009). Productivity is highly impacted by the availability of nutrients, which determines the growth rate of phytoplankton, zooplankton and fishes at higher trophic levels (Belkin et al., 2009). Fronts, which are generated at the intersection of

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Section: Interannual Variability Of Fp In the Tropical Pacificmentioning

confidence: 99%

Seasonal and Interannual Variability in the Sea Surface Temperature Front in the Eastern Pacific Ocean

et al. 2021

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“…The comparisons between CHL and CLIM can be used to illustrate the effect of ICV on ENSO and mean state. It is noteworthy that the difference between CHL and CLIM may contain other effects due to intraseasonal chlorophyll effects, which are relatively weaker compared to the magnitude of ICV (Tian et al, 2018(Tian et al, , 2019Zhang, Tian, Busalacchi, & Wang, 2019). Interestingly, our recent results show that the effect of chlorophyll on the mean state of SST is sensitively dependent on the ocean-atmosphere coupling intensity which can be represented by α.…”

Section: Experimental Designmentioning

confidence: 72%

Rectified Effects of Interannual Chlorophyll Variability on the Tropical Pacific Climate Revealed by a Hybrid Coupled Physics‐Biology Model

2021

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El Niño-Southern Oscillation (ENSO) is the strongest coupled ocean-atmosphere mode on interannual timescale, and its teleconnection effect causes the global climate and ecosystem fluctuations (Behrenfeld Abstract El Niño-Southern Oscillation (ENSO) induces large interannual chlorophyll variability (ICV) in the tropical Pacific, which modulates shortwave penetration in the upper ocean. However, the extent to which ICV can have rectified effect (higher-frequency process impacts low-frequency climate variability (i.e., ENSO) and mean state) in the tropical Pacific remains unclear. Here, a hybrid coupled physics-biogeochemistry model with tunable coupling ocean-atmosphere intensity (α) is used to examine this rectified effect. The simulations consist of a control run in which the ICV effect is represented in the model and the other with the ICV effect being purposely excluded by only reserving the climatological chlorophyll field. Results show that the ICV effect depends on α; ENSO amplitude is reduced by 12%-40% with decreased annual mean sea surface temperature by 0.05-0.4°C in the eastern equatorial Pacific when taking α = 0.8-1.15. A stability analysis reveals that the ICV effect on ENSO exhibits two feedback loops. (a) Positive (negative) chlorophyll anomalies during La Niña (El Niño) act to increase (decrease) shortwave absorption within the mixed layer, which enhances thermodynamic damping (slightly weakening ENSO amplitude). (b) Chlorophyll anomalies modulate vertical redistribution of penetrative shortwave radiation between the mixed layer and subsurface layers; this differential heating affects ocean stratification and vertical mixing, which weakens the thermocline and Ekman feedback (predominantly weakening ENSO amplitude). Additionally, ICV exhibits asymmetric effects on ENSO evolution, with the El Niño amplitude being damped stronger than La Nina; this residual effect leads to a net cooling condition in the eastern tropical Pacific.Plain Language Summary As a proxy of marine phytoplankton biomass, ocean chlorophyll not only responds to El Niño-Southern Oscillation (ENSO) phase change but also exerts a significant influence on ENSO and mean state through modulating the absorbed shortwave radiation in the upper ocean. However, the extent to which interannual chlorophyll variability (ICV) can have rectified effect (higher-frequency process impacts low-frequency climate variability and mean state) in the tropical Pacific remains unclear. In this study, we examine the rectified effect of ICV on the tropical Pacific climate by performing a series of numerical simulations. By isolating the ICV effect from the climatological mean chlorophyll field, we found that ICV acts to weaken ENSO amplitude and induces a cooling effect in the eastern equatorial Pacific, characterized by a La Niña-like pattern. A stability analysis reveals that the weakened responses of the thermocline or upwelling to the zonal wind stress (the thermocline and Ekman feedbacks) due to the ICV effect dominantly reduce ENSO amplitude. Furthermo...

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“…There are 20 vertical layers of variable thickness in the OGCM, of which the first layer (i.e., the mixed layer) is determined by surface turbulent kinetic energy generation, dynamic instability mixing, and convective mixing to remove static instabilities (Chen et al, 1994). The model is set up for the tropical Pacific domain between 30°S and 30°N, with a 1° zonal resolution; meridional resolution varies from 0.3° over 5°S-5°N to 0.5° over 5-15° and 1° for the rest of the domain; such a resolution enables the model to resolve frontal structures, for example, tropical instability waves (TIW)-induced chlorophyll perturbations in the tropical Pacific (Tian et al, 2018(Tian et al, , 2019b. There is a sponge area near the northern and southern boundaries (20-30°N and 20-30°S) where nutrients, dissolved organic nitrogen (DON) and small detritus are gradually relaxed back toward the climatological monthly means (or fixed values for DON/detritus).…”

Section: Model Descriptionmentioning

confidence: 99%

Interannual‐to‐Decadal Variations of Particulate Organic Carbon and the Contribution of Phytoplankton in the Tropical Pacific During 1981–2016: A Model Study

Wang

Murtugudde

et al. 2021

JGR Oceans

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The tropical Pacific plays a major role in the global carbon cycle because of its vast expansion and high levels of net primary production (Behrenfeld et al., 2006). There is evidence of significant export of particulate organic carbon (POC) in the tropical Pacific (Honjo et al., 2008; Murray et al., 1997). However, there have been only a few small-scale field studies on the dynamics of POC in the tropical Pacific, which have shown a large spatial and/or temporal variability in POC stock and fluxes in the upper water column (e.g.,

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A Positive Feedback Onto ENSO Due to Tropical Instability Wave (TIW)‐Induced Chlorophyll Effects in the Pacific

Cited by 15 publications

References 52 publications

Seasonal and Interannual Variability in the Sea Surface Temperature Front in the Eastern Pacific Ocean

Seasonal and Interannual Variability in the Sea Surface Temperature Front in the Eastern Pacific Ocean

Rectified Effects of Interannual Chlorophyll Variability on the Tropical Pacific Climate Revealed by a Hybrid Coupled Physics‐Biology Model

Interannual‐to‐Decadal Variations of Particulate Organic Carbon and the Contribution of Phytoplankton in the Tropical Pacific During 1981–2016: A Model Study

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